Middle/Senior Java Backend Developer

Sigma Software

Required skills

• Java / expert

• Distributed Systems / expert

• Concurrency & Multithreading / strong

• CI/CD / strong

• Caching & Data Storage / strong

• Are you passionate about building scalable backend systems that operate under real production load? We are looking for a Middle/Senior Java Backend Developer to join a long-term onsite project in Malmö, Sweden, focused on privacy-sensitive distributed services used at global scale.

• You will join a small, autonomous engineering team where ownership, technical excellence, and collaboration are highly valued. The role involves full-cycle development, from architecture discussions and implementation to deployment and production support.

• We at Sigma Software offer the opportunity to work on technically challenging products in an engineering-driven environment with modern technologies, high-quality standards, and long-term project stability.

• Customer

• Our Customer is a global technology company operating in the consumer electronics and digital services domain. The company develops large-scale platforms and infrastructure used by millions of users worldwide, with a strong focus on privacy, reliability, and seamless user experience.

• Project

• The project focuses on developing and supporting large-scale backend services operating in a privacy-sensitive environment under high production load. The team designs and maintains distributed systems with strict requirements for reliability, scalability, security, and performance. Engineers work in cross-functional teams and contribute to the entire software development lifecycle.

Requirements

• 4+ years of commercial experience in Java backend development

• Strong hands-on experience with Java and distributed systems

• Deep understanding of Java internals, including the Java Memory Model, garbage collection, concurrency, and multithreading

• Experience debugging production issues in high-load environments

• Strong knowledge of distributed systems concepts, including consistency, reliability, partitioning, and failure handling

• Experience building and scaling customer-facing backend services

• Experience with authentication and authorization mechanisms

• Hands-on experience with Cassandra, Redis, Memcached, or similar technologies

• Experience developing REST-based services using Netty or similar frameworks

• Experience with CI/CD pipelines and automated testing

• Strong analytical and problem-solving skills

• Upper-Intermediate or higher level of English

• WILL BE A PLUS

• Knowledge of cryptography standards and protocols such as PKCS, KMIP, X.509, AES, KDF, and CA

• Experience working with security- and privacy-sensitive systems

• Familiarity with machine learning systems or algorithms

• Experience with GitHub

• Experience with Maven, Docker, Kubernetes, Spinnaker, or similar tools

• Personal Profile

• Strong sense of ownership and accountability

• Ability to work independently in autonomous engineering teams

• Analytical and problem-solving mindset

• Attention to detail and engineering quality

• Strong communication and collaboration skills

• Ability to work effectively in complex distributed environments

Responsibilities

• Design, develop, and maintain scalable Java backend services and internal frameworks
• Participate in architecture discussions and contribute to technical solution design
• Build and support customer-facing services with a focus on reliability, availability, security, and performance
• Investigate and resolve complex production issues related to concurrency and distributed systems
• Work with authentication, authorization, caching, data storage, and service integrations
• Collaborate with multiple engineering teams and coordinate technical dependencies
• Participate in code reviews, automated testing, CI/CD processes, and release activities
• Prepare technical documentation and communicate technical decisions to stakeholders
• Take end-to-end ownership of features and technical solutions from concept to production